As is known in the art, a radio frequency (RF) connector is an electrical connector designed to work at RF frequencies in the megahertz range and above. RF connectors are often used with coaxial cables. One desirable characteristic of an RF connector is its ability to maintain the shielding provided by a coaxial cable as well as the characteristic of reducing changes in transmission line impedance at the interface of the coaxial cable and the RF connector. Mechanically, RF connectors typically utilize a fastening mechanism (thread, bayonet, braces, push-pull) and springs to provide a low ohmic electric contact while sparing connector surfaces (which are often gold-plated). This allows above one-thousand reconnects and reduces the required insertion force.
As is also known, research activity in the area of RF circuit design has surged in the last decade in direct response to market demand for inexpensive, high data rate wireless transceivers. Such transceivers and other circuits utilize connectors so that signals can be coupled between various modules.
One type of RF connector is a so-called “edge-launch” connector. Edge launch connectors are provided having a housing through which a signal pin is disposed to contact a circuit on a printed wiring board (PWB). The PWB is often provided as part of a circuit card assembly (CCA), for example. RF signals propagate through the edge launch connector via the signal pin. As the name implies, edge launch connectors couple to an edge of the PWB (and thus, an edge of a CCA). One attractive feature of an edge launch connector is that owing to the manner in which such connectors are coupled to CCAs, edge launch connectors often introduce a relatively small insertion loss characteristic and a relatively low voltage standing wave ratio (VSWR) characteristic when connected to circuits on the CCA. One drawback with edge launch connectors, however, is that it is relatively difficult to provide a high degree of isolation between signal pins of multiple edge launch connectors mounted in proximity to each other on a CCA.
This is particularly true when isolation levels of about 100 dB are required between connectors mounted in proximity to each other on the same CCA. In one application, for example, an RF module requires over 100 dB of isolation from individual signals operating at similar microwave frequencies on a CCA. A common problem with conventional RF edge launch connectors is RF leakage which exists between the connector and the circuit card or between the connector and a circuit card cover due to connector geometry and practical limitations in holding mechanical tolerances during manufacturing operations. To improve the isolation characteristic of a conventional edge launch connector, an EMI gasket is sometimes disposed between the mating surfaces of the CCA and the connector disposed against the edge of the CCA. One problem with this gasket approach is that the gasket can become deformed (e.g. “bunch up”) or can shear off completely resulting in gaps between the connector and CCA surfaces. This reduces the isolation characteristic of the connector.
It would, therefore, be desirable to provide an RF connector which can provide a high level of signal isolation between connector signal pins when several such signal pins are disposed in proximity on a CCA. It would also be desirable to provide an RF connector which can blindly mate to a circuit card since this provides for ease of circuit card insertion/extraction. It would also be desirable to provide an RF connector which can be mounted in close proximity with other connectors to accommodate tightly spaced signal paths necessitated by electrical and mechanical design constraints on a circuit. It would also be desirable to provide an edge launch RF connector which has one or more of the afore-mentioned characteristics.